1. Field of the Invention
The invention relates to a shed-forming mechanism and to a loom fitted with such a mechanism. The invention also relates to a method of selecting moving hooks of such a mechanism.
2. Description of Related Art
In a Jacquard type loom, a shed-forming mechanism selectively raises heddles, each having an eyelet passing a warp yarn, the yarn being situated as a function of the position of a hook secured to the top end of the heddle, either above or below a weft thread moved by the loom. Such a mechanism, as described for example in U.S. Pat. No. 7,017,618, includes moving hooks each provided with a lateral nose capable of co-operating with knives driven with vertical reciprocating motion in phase opposition. Each moving hook is fitted with a flexible metal blade for interacting with a retaining lever belonging to a selector device, thus generally obtaining satisfaction. Furthermore, a resilient abutment is placed on the path of the moving hooks where they come into the vicinity of the top dead-center point of their travel. According to the technical teaching of U.S. Pat. No. 5,839,481, the moving abutment serves to overcome the friction forces that act on a moving hook when it begins its downward movement, thus making it possible to avoid overdimensioning the return springs of the moving hooks. Such a resilient abutment has the effect of suddenly overloading the shed-forming mechanism when the moving hooks are moved upwards in the vicinity of the top dead-center points of their respective paths. The moving hooks all engage the corresponding abutments at substantially the same time, which abutments are loaded with a prestress compression spring. In addition, the resilient abutment presents a cost that reduces the overall economic performance of a mechanism incorporating such an abutment.